Printing plate clamp



Feb. 13,1945

H. M. BARBER PRINTING PLATE CLAMP ori inal Filed 001;. 2, 1942 ,INVENTOR.

Patented Feb. 13, 1945 r C. B. Cottrell & Sons Company,

a corporation of Delaware Westerly, R. 1.,

" Original application October 2, 1942, Serial No. n 460,501. Divided and this application June 12, 1943, Serial No. 490,563 a 1 t -72 Claims. (01. 191- 987) In the use ofprinting plate clamps of the type where a screw is employed for clamping the cylinder and nut to the plate support, as, for instance, a cylinder, in their plate clamping posi tion along a groove in the cylindenit has been found that at high speeds it is difiicultto maintain these clamps in their operative positions due to the strain of holding the plates on the cylinder at said high speeds. It has also been found that the clamps not only break due to the excessive strain thereon under high. speeds but.

that they also break due to the fact that the clamp screws receive directly theshocks of'the blows delivered by the pressmen against the nuts to force the clamps along the grooves into their plate clamping positions, thus causing a shearing strain on the clamp screws.

The object of my invention is to provide means for relieving this shearing or side strain on the "clamp screws when forcing the clamps into their operative position, and thus make it possible to successfully use this type of. clamp in high speed presses; said strain on the screws being elimi-' nated by the provision of coacting surfaces of various forms between the plate hooks and nuts, for absorbing the blows on the nuts and thus preventing the effect of the blows being transferred to the clamp screws.

Practical embodiments of my invention are represented on an enlarged scale in the accompanying drawing in which Fig. 1 represents a detail side view of a grooved cylinder with one form of printing plate clamp engaging one curved side edge of the printing plate;

Fig. 2 represents a section taken of the line II-II of Fig. 1; l Fig. 3 represents a section taken inthe plane of the line III-III of Fig, 2;

Fig. 4 represents an end view. of the plate clamp nut;

Fig. 5 represents a bottom plan view of the plate clamp hook;

Fig. 6 represents an end view of the hook; and

Fig. 7 represents a side view of the hook.

Fig. 8 represents a section similar to Fig. 3, showing a second form of clamp; i Fig. 9 represents a side view of the nut;

Fig. 10 represent an end view of the same;

Fig. .11 represents a bottom plan view of the hook; 1 Fig. 12 represents an end view of the same; and

Fig. 13 represents aside view of the hook.

The printing plate support which is herein in the plane shown as a cylinder, is denoted by l, andone of its usual spiral grooves by 2, which groove may be of any well known tional shape.

The curved printing plate is denoted by 3 and its curved beveled edge by 4.

The plate clamp comprises the nut 6, the plate hook land the clamp screw 8. In the embodiment shownin Figs. 1 to 9 inclusivethe plate hook I is shown as provided with a guide member 9 which is provided with parallel side edges 10,10, slidably engaging the side walls of the groove 2 and thus forming an extended bearing for guiding the plate hook 1 along the groove with the nut 6, into and out of engagement with or approved cross sec the beveled edge 4 ofthe printing plate 3. It

will be noted that the guide member 9 projects under the beveled edge of the plateand forms together with the beveled edge of the plate hook an angular recess for receiving the beveled edge of the plate, thereby permitting the hook from riding up thereon.

It will be understood that the clamp screw 8.

passes freely through the plate hook I and its guide member 9 into threaded engagement with the nut 6. n

This nut G in both of theembodiments illustratedis shown as having a shallow recess ll adapted to receive the guide member 9 of the plate hook when the parts of the clamp are assembled.

Coacting surfaces are provided on the plate hook guide member 9 and the nut 6 for preventmember 9 of the plate hook l is shaped to form two anguIarsurfacesIZ, 13 which coact with corresponding angular surfaces [4, l5 of the adjacent end .wall of the said guide member; the coacting surfaces [2 and I4 being parallel with the back edge of the plate hook and the coacting surfaces l3 and I5 beingatright angles to the cylinder groove 2.

In the embodiment shown in Figs. 8 to 13 inclusive the uprisinginner wall of the shallow recess H in the nut 6 forms a diagonal surface 16 which coacts with a corresponding. diagonal surface 19* at one end of the hook guide mem- In both of the embodiments the coactlng sur-- faces of the plate hook and nut are so located that they, rather than the clamp screws, will reapplication filed October 2, 1942', Serial No.

It is evident that various ichang'es m'ay be iresorted to in the construction, form and arrangement of the several parts withoutdepantin-g from the spirit and scope ofmy invention, aniikhence I do not intend to be limited to 'the particular embodiments herein shown and described, but

What I claim is:

.1. Inaplate clamp adapted to betmoved along a grooved-support .into engagement with an .edge of a printing plate, a hook provided withazg'ui-de member rsl-idablein a groove of said support, 9.

nut having a shallow recess for housing the guide member, and a clamp screw passing freely through the hook and guide member into threaded engagement with the nut, said guide member having a diagonal surface and'said nut having a corresponding coacting diagonal surface for preventing the; hook friom exerting :side strain on the screw when the is subjected to end- Wise force.

l -:2. In a plate clampadapted to be moved along a grooved support into engagement with an edge of a printing plate, a hook provided with a guide member :slidable a groove of said support, a

.- znu-it having za shaillow recess for housing the guide member, and -a clanop screw passing freely through the hook and guide member into threaded engagementwith the nut, said guide member having ia ngu'l ar surfaces and said recess having corresponding coacting angular surfaces for preveritingthe hook from exerting side strain on the screw when the nut is subjected to endwise force. V ML BA 13 ER. 

